Biology is the scientific study of life. The word “biology” has been derived from two Greek words; ‘bios’ meaning ‘life’ and ‘logos’ meaning ‘thought or reasoning’. In the course of biology, we will study how man has thought about living things. To understand and appreciate nature, it is essential to study the structures, functions and related aspects of living organisms. The study of living organisms also provides information and remedies to human problems regarding health, food, environment etc. Molecular biology (biochemistry) deals with the study of the molecules of life; e.g. water, proteins, carbohydrates, lipids, and nucleic acids.